find(1) / -perm /4000
search for files in a directory hierarchy
find [-H] [-L] [-P] [-D debugopts] [-Olevel] [path...] [expression]
-perm mode
       File's permission bits are exactly mode (octal or symbolic).  Since an exact match is required, if
       you want to use this form for symbolic modes, you may  have  to  specify  a  rather  complex  mode
       string.  For example -perm g=w will only match files which have mode 0020 (that is, ones for which
       group write permission is the only permission set).  It is more likely that you will want  to  use
       the  `/' or `-' forms, for example -perm -g=w, which matches any file with group write permission.
       See the EXAMPLES section for some illustrative examples.

-perm -mode
       All of the permission bits mode are set for the file.  Symbolic modes are accepted in  this  form,
       and  this is usually the way in which would want to use them.  You must specify `u', `g' or `o' if
       you use a symbolic mode.   See the EXAMPLES section for some illustrative examples.

-perm /mode
       Any of the permission bits mode are set for the file.  Symbolic modes are accepted in  this  form.
       You  must  specify  `u', `g' or `o' if you use a symbolic mode.  See the EXAMPLES section for some
       illustrative examples.  If no permission bits in mode are set, this test  matches  any  file  (the
       idea here is to be consistent with the behaviour of -perm -000).

-perm +mode
       Deprecated,  old  way  of  searching  for  files with any of the permission bits in mode set.  You
       should use -perm /mode instead. Trying to use the  `+'  syntax  with  symbolic  modes  will  yield
       surprising results.  For example, `+u+x' is a valid symbolic mode (equivalent to +u,+x, i.e. 0111)
       and will therefore not be evaluated as -perm +mode but instead as the exact mode  specifier  -perm
       mode  and  so  it  matches files with exact permissions 0111 instead of files with any execute bit
       set.  If you found this paragraph confusing, you're not alone - just use -perm /mode.   This  form
       of  the  -perm test is deprecated because the POSIX specification requires the interpretation of a
       leading `+' as being part of a symbolic mode, and so we switched to using `/' instead.
source manpages: find